The proposed research will explore the relationship between improvements in auditory discrimination and neuronal plasticity in the primary auditory cortex (A1) of the rat. By chronically recording from a small population of cortical neurons in the awake and behaving rat during operant training, the proposed study seeks to characterize behavioral improvements and associated cortical plasticity as they develop together. The proposed experiments will selectively reinforce discrimination of either spectral or temporal features contained within a single acoustic stimulus, with the intention of elucidating the rules by which attention regulates the bond between the acoustic environment and lasting changes in the functional representation of elementary sound features in A1. The proposed studies will specifically test the hypothesis that attention, and subsequent improvements in discriminative ability, can be selectively focused on either the spectral or temporal components of a single "complex" acoustic stimulus. These experiments will additionally characterize the nature and time course of plasticity in A1 relative to the improvements in auditory discrimination ability. Finally, the proposed research will attempt to identify the types of cortical plasticity that are most closely associated with improvements in auditory discrimination in hopes of identifying neural targets for the remediation of auditory processing deficits in humans.